OP, even if you do manage to get that fouling out of the bore, IMHO, it's not going to be the jewel you're hoping for.
Sweet's 7.62 solvent is about as aggressive as a commercial grade mixes come.
Taking your barrel to an engine repair shop, for a bath in their Caustic Soda tank, will definitely remove everything, including whatever finish is on it.
I have done the soaking in hot Caustic tanks on several occaisions. It works but whatever polishing is present before it goes in won't be there when it comes out.
If the Caustic tank works in the manner, the tanks I used does, it's basicly an electrolocis process and when pulled out, immediately immersed in hot/clean water, then blown off and usually washed with a fixing solvent after to slow down corrosion.
The metal will be absolutely bare and it will start showing rust within a few hours.
This rust is extremely difficult to get rid of, even bluing, a rusting process, won't stop it. The only thing that will stop the rust is OIL or a spray on coating to seal the metal from air/moisture.
Those tanks were made for cleaning Cast Steel Engine Blocks, Heads.
I used to go so far as to make up my own bore cleaner, specifically for Cupro Nickel fouling.
It had a very high concentration of Ammonia. It contained appx 25% concentrated ammonia which isn't available off the shelf and may require a special permit to purchase.
I had a source for the concentrated ammonia, which I mixed, according to a recipe used by military armorers back in the day.
I won't use it anymore, it's dangerous to humans, corrosive and if left in a bore for to long, it will damage the bore.
I exclusively use WIPE OUT.
Like Ganderite, I'm lazy and when I'm cleaning firearms, there are usually several at the same time.
Someone mentioned not to leave Wipe Out in the bore.
I contacted the people that manufacture it and was told they even suggest leaving it in the bore for storage, especially if you have an excellent bore without pits/frosting.
They suggest that it should be wiped out before shooting.
I was uncomfortable with that, so I did a take off barrel, with a bend, and pushed a loose patch soaked in Wipe Out through it and put it somewhere that I would come across it again, if I forgot why it was standing nose down in a plastic container. So, I put a tag on it explaining why it was there.
Eight months later, I wet another patch with Wipe out, ran it down the bore, followed by a clean, tight patch. It came out dark blue/green, after what I thought was a clean bore.
There was no visible damage to the bore and after a second pass with another clean, tight patch there were a few streaks of color. the third patch just had that faint gray color that indicates a bore that's been cleaned right down to the original metal.
NO RUST OR PITS, just a very shiny bore.
I commonly leave Wipe Out in a bore overnight. I never plug the bore and fill it as that's just a waste of a rather expensive product.
I don't purchase the "foaming" type because I use a lot of it and find that I can do three times as many barrels for the same cost with the fluid on a loose patch type.
I don't find the "Enhancer" helps at all.
If you use Sweet's 7.62 cleaner, which has appx 8% ammonia in solution, DON'T LEAVE IT IN YOUR BORE OVERNIGHT.
I don't like to leave it for more than fifteen minutes, if I know the bore is excellent or on a match rifle.
Sometimes, especially with a worn/pitted bore I will leave it for a couple of hours. That means it has to be wiped clean, with alcohol and dried, then sealed with a good oil or very light grease, then cleaned out again at the range before shooting.
Bores cleaned in this manner usually require a couple or even several fouling shots before they shoot accurately.
That means you have to find where that accuracy starts and where excess fouling causes it to break down.
Lots of folks never clean a bore all the way down to the original metal.
In many cases a quick pass with Wipe Out, when the accuracy goes awry, then left for 20 minutes is enough to get the rifle back to the sweet spot, after a fouling round.
